1. Field of the Invention
This invention relates generally to a novel form of an electric generator that produces electric energy by fuel cell-like principles.
2. Description of Related Art
Fuel Cell
A fuel cell is a device that converts chemical energy from a fuel into electricity through a chemical reaction between positively charged hydrogen ions and oxygen or another oxidizing agent. Fuel cells are different from batteries in that they require a continuous source of fuel and oxygen or air to sustain the chemical reaction, whereas in a battery the chemicals present in the battery react with each other to generate an electromotive force (EMF). Fuel cells can produce electricity continuously for as long as these inputs are supplied.
There are many types of fuel cells, but most consist of an anode, a cathode, and an electrolyte that allow positively charged hydrogen ions (or protons) to move between the two sides of the fuel cell. The anode is a catalyst that causes the fuel to undergo oxidation reactions that generate positive hydrogen ions and electrons. The hydrogen ions are drawn through the electrolyte after the reaction. At the some time, electrons are drawn from the anode to the cathode through an external circuit, producing direct current electricity. At the cathode, hydrogen ions, electrons, and oxygen react to form water.
As the main difference among fuel cell types is the electrolyte, fuel cells are classified by the type of electrolyte they use and by the difference in startup time ranging from one second for proton exchange membrane fuel cells (PEM fuel cells, or PEMFC) to 10 minutes for solid oxide fuel cells (SOFC). SOFC fuel cells transport an oxygen ion (rather than transporting a proton), but the overall redox reaction to produce electricity is essentially the same as PEM fuel cells. Individual fuel cells produce relatively small electrical potentials, about 0.7 volts, so cells are “stacked,” or placed in series, to produce sufficient voltage to meet an application's requirements. Electrical current is relative to the size or surface area of a given cell.
In addition to electricity, fuel cells produce water, heat and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions. The energy efficiency of a fuel cell is generally between 40%-60%, or up to 85% efficient in cogeneration if waste heat is captured for use. The heat is produced at the cathode, where the protons and electrons combine with the oxygen to produce water.
A. Types of Fuel Cell Designs
Fuel cells come in many varieties; however, they all work in the same general manner. They are made up of three adjacent segments: the anode, the electrolyte, and the cathode. Two chemical reactions occur at the interfaces of the three different segments. The net result of the two reactions is that fuel is consumed, water or carbon dioxide is produced, and an electric current is produced, which can be used to power electrical devices, normally referred to as the load.
At the anode, a catalyst oxidizes the fuel, usually hydrogen, turning the fuel into a positively charged ion and a negatively charged electron. The electrolyte is a substance specifically designed so ions can pass through it, but the electrons cannot. The freed electrons travel through a wire producing the electric current. The ions travel through the electrolyte to the cathode. Once reaching the cathode, the ions are reunited with the electrons and the two react with a third chemical, usually oxygen, to form water or carbon dioxide.
The most important design features in a fuel cell are:                The electrolyte substance which usually defines the type of fuel cell.        The fuel that is used, most commonly hydrogen.        The anode catalyst breaks down the fuel into electrons and ions, usually very fine platinum powder.        The cathode catalyst turns the ions into the waste chemicals like water or carbon dioxide. The cathode catalyst is often made up of nickel but it can also be a nanomaterial-based catalyst.        
A typical fuel cell produces a voltage from 0.6 V to 0.7 V at full rated load. Voltage decreases as current increases, due to several factors:                Activation loss        Ohmic loss (voltage drop due to resistance of the cell components and interconnections)        Mass transport loss (depletion of reactants at catalyst sites under high loads, causing rapid loss of voltage).        
To deliver the desired amount of energy, the fuel cells can be combined in series to yield higher voltage, and in parallel to allow a higher current to be supplied. Such a design is called a fuel cell stack. The cell surface area can also be increased, to allow higher current from each cell. Within the stack, reactant gases must be distributed uniformly over each of the cells to maximize the power output.
1. Proton Exchange Membrane Fuel Cells (PEMFCs)
In the archetypical hydrogen-oxide proton exchange membrane (PEM) fuel cell design, a proton-conducting polymer membrane (the electrolyte) separates the anode and cathode sides. This was called a “solid polymer electrolyte fuel cell” (SPEFC) in the early 1970s, before the proton exchange mechanism was well-understood. The PEM will transport H+/D+, but not electrons.
On the anode side, hydrogen diffuses to the anode catalyst where it later dissociates into protons and electrons. These protons often react with oxidants causing them to become what are commonly referred to as multi-facilitated proton membranes. The protons are conducted through the membrane to the cathode, but the electrons are forced to travel in an external circuit (supplying power) because the membrane is electrically insulating. On the cathode catalyst, oxygen molecules react with the electrons (which have traveled through the external circuit) and protons to form water.
The different components of a PEMFC are;                1. bipolar plates,        2. electrodes,        3. catalyst,        4. membrane, and        5. necessary hardware.        
The materials used for different parts of the fuel cells differ by type. The bipolar plates may be made of different types of materials, such as, metal, coated metal, graphite, flexible graphite, C—C composite, carbon-polymer composites etc. The membrane electrode assembly (MEA) is referred as the heart of the PEMFC and is usually made of a proton exchange membrane sandwiched between two catalyst-coated carbon papers. Platinum and/or a similar type of noble metals are usually used as the catalyst for PEMFC. The electrolyte could be a polymer membrane.
2. Phosphoric Acid Fuel Cell (PAFC)
In these cells, phosphoric acid is used as a non-conductive electrolyte to pass positive hydrogen ions from the anode to the cathode. These cells commonly work in temperatures of 150 to 200 degrees Celsius. Phosphoric acid, the electrolyte used in PAFCs, is a non-conductive liquid acid which forces electrons to travel from anode to cathode through an external electrical circuit. Since the hydrogen ion production rate on the anode is small, platinum is used as catalyst to increase this ionization rate. A key disadvantage of these cells is the use of an acidic electrolyte, which increases the corrosion or oxidation of components exposed to phosphoric acid.
3. High-Temperature Fuel Cells
a) SOFC
Solid oxide fuel cells (SOFCs) use a solid material, most commonly a ceramic material called yttria-stabilized zirconia (YSZ), as the electrolyte. Because SOFCs are made entirely of solid materials, they are not limited to the flat plane configuration of other types of fuel cells and are often designed as rolled tubes. They require high operating temperatures (800°-1000° C.) and can be run on a variety of fuels including natural gas.
SOFCs are unique since in those, negatively charged oxygen ions travel from the cathode (positive side of the fuel cell) to the anode (negative side of the fuel cell) instead of positively charged hydrogen ions travelling from the anode to the cathode, as is the case in all other types of fuel cells. Oxygen gas is fed through the cathode, where it absorbs electrons to produce oxygen ions. The oxygen ions then travel through the electrolyte to react with hydrogen gas at the anode. The reaction at the anode produces electricity and water as by-products. Carbon dioxide may also be a by-product depending on the fuel, but the carbon emissions from an SOFC system are less than those from a fossil fuel combustion plant. The chemical reactions for the SOFC system can be expressed as follows:2H2+2O2−→2H2O+4e−  Anode Reaction:O2+4e−→2O2−  Cathode Reaction:2H2+O2→2H2O  Overall Cell Reaction:
SOFC systems can operate on fuels other than pure hydrogen gas. However, since hydrogen is necessary for the reactions listed above, the fuel selected must contain hydrogen atoms. For the fuel cell to operate, the fuel must be converted into pure hydrogen gas. SOFCs are capable of internally reforming light hydrocarbons such as methane (natural gas).
b) Hydrogen-Oxygen Fuel Cell (Bacon Cell)
This cell consists of two porous carbon electrodes impregnated with a suitable catalyst such as Pt, Ag, CoO, etc. The space between the two electrodes is filled with a concentrated solution of KOH or NaOH which serves as an electrolyte. 2H2 gas and O2 gas are bubbled into the electrolyte through the porous carbon electrodes. Thus, the overall reaction involves the combination of hydrogen gas and oxygen gas to form water. The cell runs continuously until the reactant's supply is exhausted.
c) MCFC
Molten carbonate fuel cells (MCFCs) require a high operating temperature, 650° C. (1,200° F.), similar to SOFCs. MCFCs use lithium potassium carbonate salt as an electrolyte, and this salt liquefies at high temperatures, allowing for the movement of charge within the cell—in this case, negative carbonate ions.
Like SOFCs, MCFCs are capable of converting fossil fuel to a hydrogen-rich gas in the anode, eliminating the need to produce hydrogen externally. The reforming process produces CO2 emissions. MCFC-compatible fuels include natural gas, biogas and gas produced from coal. The hydrogen in the gas reacts with carbonate ions from the electrolyte to produce water, carbon dioxide, electrons and small amounts of other chemicals. The electrons travel through an external circuit producing electricity and return to the cathode. There, oxygen from the air and carbon dioxide recycled from the anode react with the electrons to form carbonate ions that replenish the electrolyte, completing the circuit. The chemical reactions for an MCFC system can be expressed as follows:CO32−+H2→H2O+CO2+2e−  Anode Reaction:CO2+½O2+2e−→CO32−  Cathode Reaction:H2+½O2→H2O  Overall Cell Reaction:
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those skilled in the art upon a reading of the specification and a study of the drawings.